1. Field of the Invention
The present invention relates to a digital broadcast system, and more particularly, to a method and apparatus capable of transmitting and receiving data in an improved multi-channel digital broadcasting system while also compatible with existing digital broadcasting systems.
2. Description of the Related Art
In recent years, advanced communication techniques have been introduced to solve noise problems by using advanced encoding schemes that achieve near-Shannon capacity performance. The advanced encoding schemes include parallel concatenated convolutional codes (PCCC), serially concatenated convolutional codes (SCCC), low-density parity check codes (LDPC), etc.
However, many of the contemporary digital broadcasting systems and their corresponding receivers in use today were developed or standardized before the discovery of the advanced encoding schemes. The digital audio broadcast (DAB) system, also known as Eureka-147 project, is an example of the digital broadcasting systems that were developed in the late 1980s and are now widely used worldwide.
FIG. 1 is a block diagram of a transmitting apparatus for a conventional multi-channel digital broadcasting system. Referring to FIG. 1, the apparatus includes a control channel generating unit 10, a main service channel (MSC) generating unit 20, an MSC multiplexer 30, a transmission frame multiplexer 40, a fast information channel (FIC) and MSC symbol generator 50, and an orthogonal frequency division multiplexed (OFDM) signal generator 60.
The control channel generating unit 10 includes a fast information block (FIB) assembler 11, a scrambler 13, and a convolutional encoder 15 in order to generate an FIC containing information regarding a main service channel, based on control data.
The MSC generating unit 20 includes a plurality of sub channel blocks 20-1 through 20-N that generate a plurality of sub channels based on information data. Each of the sub channel blocks (20-1 through 20-N) includes a scrambler 21-1 through 21-N) that scrambles received data, a non-systematic non-recursive convolutional (NSC) encoder (23-1 through 23-N) that encodes the data received from the scrambler (21-1 through 21-N), a puncturing unit (25-1 through 25-N) that punctures the data received from the NSC encoder (23-1 through 23-N), and a time-interleaver (27-1 through 27-N) that performs time-interleaving on the data received from the puncturing unit (25-1 through 25-N).
The MSC multiplexer 30 multiplexes the data received via the sub channel blocks 20-1 through 20-N of the MSC generating unit 20, and outputs the multiplexed result.
The transmission frame multiplexer 40 generates a transmission frame based on the multiplexed result received from the MSC multiplexer 30 and a signal received from the control channel generating unit 10 and outputs the transmission frame.
The FIC and MSC symbol generator 50 generates FIC and MSC data symbols for the transmission frame received from the transmission frame multiplexer 40.
The OFDM signal generator 60 generates an OFDM signal from the data received from the FIC and MSC symbol generator 50 and data received from a synchronization channel symbol generator (not shown).
FIG. 2 is a diagram illustrating a data structure of a transmission frame for a conventional multi-channel digital broadcasting system. Referring to FIG. 2, a transmitting apparatus for the conventional digital broadcasting system, combines three channels to generate a transmission frame and transmits the transmission frame. The transmission frame includes a synchronization channel 110, an FIG. 120, and an MSC 130. The MSC 130 includes a plurality (N) of N sub channels 130-1 through 130-N.
The synchronization channel 110 contains information needed to perform basic demodulator functions, such as transmission frame synchronization, automatic frequency control, channel state estimation, and transmitter identification.
The FIC 120 contains plural pieces of information that a receiving apparatus (not shown) must rapidly access, and particularly, multiplexing configuration information.
The MSC 130 transmits components for audio, video, or data services. The MSC 130 includes a plurality (N) of sub channels 130-1 through 130-N that are individually (independently) convolutionally encoded and time-interleaved.
A transmitting apparatus, such as that shown in FIG. 1, for a conventional multi-channel digital broadcasting system, uses conventional encoding schemes. Thus, in order to realize a transmitting apparatus, for a multi-channel digital broadcasting system, using advanced encoding schemes, e.g., serially concatenated convolutional codes (SCCC), an encoder using SCCC must be included into the system of FIG. 1. However, in this case, a receiving apparatus designed for a conventional multi-channel digital broadcasting system using conventional encoding schemes must be replaced with a receiving apparatus that includes a decoder using SCCC, thereby making new broadcasting system incompatible with existing receiving equipment.